Design of the Ring Groove
The purpose of the ring groove is to absorb the forces transmitted from the retained machine component into the Seeger retaining system. As shown in Figure 1, the groove is identified by the groove diameter d2 and, dependent on it, by the groove depth t and the groove width m.
Figure 1: Seeger-Ring Groove
Groove Diameter d2 and Groove Depth t
The values given in the data charts for the groove diameter d2 provide rings that fit in their grooves with a relatively large pre-stress. This pre-stress is required when large mass forces occur in the ring plane in opposition to the stress of the rings, e.g. centrifugal forces at high shaft speeds. Here, the groove depth t can be reduced in favour of an increased pre-stress. In designs where such mass forces do not occur, the groove depth and thus the groove area AN and also the load bearing capacity of the groove FN can be enlarged. The limit is posed by the diameter in unstressed condition d3 i.e. for shaft rings d2 min = d3 max and for bore rings d2 max = d3 min.
Groove Width m
The values given in the data charts are minimum values which are recommended for the usual applications of Seeger retaining systems in rectangular grooves and for unilateral force transmission. Depending on the design of the machine component or mating part pressing on the ring, the groove may be widened towards the relieving side. Wide grooves are much easier to recess than narrow ones. However, if the Seeger retaining system is to alternately transmit the forces onto the groove walls in both directions, the groove width m must be adapted to the ring thickness in accordance with manufacturing capabilities.
Shape of the Groove
The rectangular groove is still the standard form. It can be rounded on the load side with r = 0.1 s (10% of the ring thickness s) without noticeably influencing the fit of the ring (see Figure 2a). Figure 2b shows a groove slanted towards the relieved side. Figures 2c and 2d show grooves systematically rounded on the load side. Here, sharp-edged rings make optimum user of the groove area. Figure 2e depicts a groove with a relief groove reducing the notch effect.
Figure 2: Groove Shape
a = rectangular groove
b = slanted groove
c and d = rounded grooves
e = groove with relief groove
Notch Effect of the Groove
Matching sharp-edged grooves for Seeger retaining rings leads to a notch effect. In the case of materials with a notch sensitivity corresponding to CK 45 Rm = 630 N/mm2, the following notch effect figures can be expected on a rectangular groove:
30 mm: ß K = 2,24
80 mm: ß K = 2,60
These notch effect figures can be reduced by rounded grooves as shown in Figures 2c and 2d and by a relief groove as shown in Figure 2e.
Compensating axial Play
Spring compensation It is not possible using normal, flat Seeger retaining systems to assemble machine components without axial play. Attention has been drawn to elastic compensation of play with the aid of AL and respectively JL rings. This axial compensation, i.e. a springing effect of the rings, however is not permissible in all designs. Bevelled Rings In this case, it would be an option to use Seeger bevelled rings, which permit play-free retaining of the mating machine component. Select Fit Series Rings The use of selected incremental thicknesses of Seeger retaining systems is possible to rigidly reduce play in steps. These are typically ground rings and are available in graduations and thickness tolerances of between 0.02 mm and 0.05 mm. Support washers can also be manufactured with graduated thicknesses. Seeger-Orbis should be consulted before defining the largest and smallest thickness as well as the smaller thickness tolerances.
Positive radial Retention of Seeger Retaining Systems
Viewed axially, the Seeger ring joint is a positive one. However, radially, the elastic ring is held in the groove only by its own tension. Positive radial retention of rings in the groove may be advantageous in the event of high axial forces and when placing high demands on safety, namely:
- The ring cannot work its way out of the groove.
- Use of deeper grooves means that there is no need for pre-stress and thus
- the groove has a greater load bearing capacity,
- circular contact is provided in the groove and
- the rpm speed limitation of the shaft rings is eliminated.
Figure 3: Overlapping of a Seeger ring (left) and a circular wire circlip (right)
On the left, Figure 3 shows overlapping of a Seeger ring and on the right, of a circular wire ring. The latter can also be overlapped with a chamfer instead of the quarter circle-shaped recess. More or less a centrical design of the rings is a precondition for overlapping. This is ensured by all circlips, by the Seeger V rings and by the K rings. In the case of Seeger-Rings to DIN 471/472, this applies only to the versions 10 and 11 shown in catalogue, left Illustration.
Overlapping of the fitted ring as shown in Figure 3 is only possible when the machine component can be pulled back before assembly and pressed on again later, a precondition which is not always possible. The Seeger Handbook gives further in-depth information on design details of Seeger-Ring assemblies.